BACTE LAB LA10 and 11

Question 1

Visual culture characteristics of a bacterial colony on agar
plate

Answer 1

Colonial Morphology

Question 2

what is the Smibert and Krieg Protocol

Answer 2

1. Measure the colony diameter in millimeters
2. Describe the pigmentation.
3. Describe the form, elevation, and margin. Also indicate whether the colony is smooth, rough or mucoid.
4. Record the opacity of the colonies
5. Determine texture when tested with a needle.

Question 3

Color and Pigment of Serratia marcescens

Answer 3

Red- Prodigiosin

Question 4

Color and Pigment of Pseudomonas aeruginosa

Answer 4

Blue Green- Pyocyanin

Question 5

Color and Pigment of Staphylococcus aureus

Answer 5

Yellow- Zeaxanthin

Question 6

Why is colonial morphology performed

Answer 6

Features of the colonies may help to pinpoint the identity of the bacterium.

It gives us idea how many species are there in a specimen.

Question 7

who discovered Gram Stain

Answer 7

Hans Christian Gram (1884)

Question 8

most commonly used stain in the clinical microbiology laboratory

Answer 8

GRAM STAIN

Question 9

Color of Gram Positive Bacteria

Answer 9

Blue to Purple

Question 10

Color of Gram Negative Bacteria

Answer 10

Pink

Question 11

Clinical samples are directly smeared
and stained for gram-staining

Answer 11

Direct Gram Staining/Direct Smear

Question 12

Provides a preliminary diagnosis regarding the infectious agents and
frequently is used to direct initial therapies for the patient

Answer 12

Direct Gram Staining/Direct Smear

Question 13

Prepared from bacterial colonies growth in culture medium

Answer 13

Indirect Gram Staining/Indirect Smear

Question 14

Used to determine subsequent testing for identifying and characterizing the
organisms isolated from the patient specimen

Answer 14

Indirect Gram Staining/Indirect Smear

Question 15

Principle of Gram Stain

Answer 15

Based on the differences in composition
of peptidoglycan of Gram (+) and Gram (-) Bacteria

Question 16

cell walls, which contain
thick peptidoglycan with numerous teichoic acid cross-linkages

Answer 16

Gram-positive Bacteria

Question 16

cell walls, which consist
of a thinner layer of peptidoglycan and
an outer lipid bilayer that is dehydrated
during decolorization

Answer 16

Gram-negative Bacteria

Question 17

Primary Stain of the Gram Stain

Answer 17

Crystal Violet (hexamethyl-p-rosaniline chloride)

Question 18

Crystal Violet is a basic chemical dye that consists of _____________________ charges

Answer 18

positive or cationic

Question 19

Crystal Violet dye will adhere to the organisms whose membranes have ______________________ charges

Answer 19

negative or anionic

Question 20

Crystal Violet Has
affinity to the _________________ layer

Answer 20

peptidoglycan

Question 21

Mordant used for Gram Stain

Answer 21

Gram’s Iodine

Question 22

Time of application of the Mordant

Answer 22

1 Minute

Question 23

Time of application of the Primary Dye

Answer 23

1 minute

Question 24

interacts with CV(+) to form large complexes (insoluble to water) and to replace the smaller chloride in the stain molecule

Answer 24

Gram’s iodine

Question 25

* Most critical part of the procedure/component * Will differentiate the bacteria

Answer 25

Decolorizer

Question 26

What is the Decolorizer for Gram Stain

Answer 26

Acetone Alcohol

Question 27

Time of Application of Decolorizer

Answer 27

Less than 10 seconds

Question 28

Effect of Acetone Alcohol to Gram (+) bacteria

Answer 28

Peptidoglycan is dehydrated and shrunk, trapping the CV-I complex inside

Question 29

Effect of Acetone Alcohol to Gram (-) bacteria

Answer 29

Damages these thin lipid walls (LPS) and allows the stain complex to wash out

Question 30

Counter Stain for Gram Stain

Answer 30

Safranin

Question 31

Time of Application of Counter Stain

Answer 31

1 minute

Question 32

Cells in a direct smear from a patient specimen, such as epithelial cells, white blood cells, red blood cells, and amorphous background material, should appear ______________________ if the Gram stain procedure was performed correctly.

Answer 32

pink (gram-negative)

Question 33

Bordetella pertussis leave safranin on for _______________ or replace safranin with _____________________

Answer 33

2 MINUTES, 0.2%, BASIC FUCHSIN

Question 34

POSITIVE CONTROL FOR GRAM-STAINING

Answer 34

Staphylococcus aureus

Question 35

NEGATIVE CONTROL FOR GRAM STAINING

Answer 35

Escherichia coli

Question 36

gram-staining for Fungi

Answer 36

Hucker's Modification (CV+ ammonium oxalate)

Question 37

All cocci are gram(+) EXCEPT

Answer 37

NeVerMind (Neisseria, Veillonella, Moraxella- gram negative cocci)

Question 38

All bacilli are gram(-) EXCEPT

Answer 38

MCC-BELL (Mycobacteria, Corynebacterium, Clostridium, Bacillus, Erysipelothrix, Lactobacillus, Listeria)

Question 39

Higher forms of organisms like ______________________ are gram (+)

Answer 39

Actinomyces, Nocardia, Streptomyces, yeast and molds

Question 40

All ________ organisms are reported as Gram (-)

Answer 40

spiral

Question 41

NOT GRAM STAINED: ___________________________

Answer 41

Rickettsia, Chlamydia, Mycoplasma, Ureaplasma, Spirochetes